Alloying steel



Patented May 12, 1942 aLLoYmG sirnnr. Arthur Linz, New York, N. Y., assignor to Climax Molybdenum Company, New

poration of Delaware York, N. Y., a cor- No Drawing. Application January 18, 1940,

. Serial No. 314,447

4 Claims. (01. 75-133)" The present invention relates to alloying tungsten with ferrous metals and more particularly to a .novel and improved process and coni'position for introducing tungsten into steel during the alloying process. g

Objects and advantages of the invention will be set forth in part hereinafter and in part will I be obvious herefrorn, or may be learned by practic with the invention, the same being realized and attained by means of the steps, processes and instrumentalities pointed out .in the appended claims.

The invention consists in t ovel'steps, proc- 'esses, combinations and provements herein shown and described.

Heretofore, tungsten-bearing ferrous alloys have been commercially produced by adding calcium tungstate, ferro-tungsten or some tungstenbearing mineral such as wolframite, scheelite,

ever, due to the relatively great specific gravityof farm-tungsten, it tends to sink in'the molten steel and it is difiicult to'dissolve and thereby obtain a homogeneous alloy. Many of the alloying materials also have the disadvantage that they are absorbed only slowly into the steel bath, and at the same time introduce undesirable impurities. e In accordance with the present invention, the alloys are produced by adding to the bathot molten steel at least a substantial part of the. desired amount of tungsten in the form of an oxide of tungsten; such as tung'stic oxide (W03) tungstendioxide (W02), of a suboxide (W0, W205, W203, W403, W509 or W401i), The tungsten oxide is, rapidly reduced, and at the same time the molten metal is vigorously boiled so that a homogeneous mixture of the added tungsten as well asany previously added in-' gradients are insured. t

Where the tungsten alloy'steel is produced in an electric furnace, it is usual to cover the ferroiis. alloy with a reducing slag; (carbide slag), and if that\be the-case, the reduction of the sten oxide purifies the alloy and removes certrain of the alloying ingredients such as chromium and vanadium, which can then be caused to go back into the alloy by the addition to the slag of ferro-silicon orsome other reducing agent.

For convenience in handling, and in order to reduce'the amount of oxidation caused by the tungsten oxide, it is preferably prepared for use by mixing it with some carbonaceous, reducing material, such as still-pitch, and'by molding this mixture into briquettes each of which may contain a uniform amount of tungsten.

5 oxide briquettes, the

ln case only a portion of the desired amount of tungsten is added in the form of tungstic added in the form of ferro-tungsten and this addition preferably takes place before the addition of the tungstic oxide, so that the vigorous mixing effect accompanying the reduction of the ferberite or hubernite to the molten steel. Howso tungstic oxide insures a thorough mixing of the molten ingredients. Instead ofusing ferro-tungsten for a-po tion of the tungsten addition, the lower oxides of tungsten may be employed alone orin combine,- tion with tungsticoxide, and where an alloy rich in tungsten is to be produced, this will be advantageous over using tungstic oxideas the boiling will be less vigorous and more easily controlled.

Referring now indetail to the present preferredmanner of carrying out the invention, the powdered tungstic oxide ,is mixed with about one tenth its weight of still-pitch, and this mixture is formed into uniform briquettes each of which may conveniently contain five pounds of tungsten. Where lower oxides of tungsten are used, a lesser proportion of carbonaceous materiarmay be employed, enough being used, how- I brought to the proper temperature in theusual tungstic or other tungsten oxide not only ren- .ders the tungsten available for solution in' the molten steel, the formation of other oxides byreduction of tungstic oxide or other tungsten oxide tends to oxidize certain of the impurities in the molten alloy and to cause them to rise and go into the slag. Thus, the use of the tungever, to completely reduce-the oxide.

The alloying ingredients for the desired al loy, excluding only the tungsten oxide briquettes, are charged in the electric furnace, and

manner. Thereafter, after sufllcient time has been allowed for the absorption otwha'tever ferro-tun'gsten may be used, theremainderof the tungsten requirements is added in the form of the tungsten oxide briquettes. As these are added,

the .power supplied to the electric furnace may be controlled or reduced so as to .control the heat I of the mixture and toprevent too vigorous agi-- tation or boiling as'the tungsten oxide is reduced.

After the reduction of tungsten oxide has been completed, the heating of the alloy is continued and, if the process is being carried out with an remainder is preferablybeen oxidized and to cause the reduction from the slag and reabsorption of the chromium and vanadium previously added to the alloy.-

For usual tungsten alloys, the entire amount of tungsten may be supplied by tungstic oxide briquettes, but for larger amounts of tungsten and where tungstic oxide briquettes alone might cause too vigorous boiling, a part of the tungsten may be added in the form offerro-tungsten as described above, or some or all of the briquettes may be of one or more of the lower oxides of tungsten, these lower oxides producing less gas and a less vigorous boiling of the molten metal.

The invention in its broader aspects is not limited to the specific processes and steps described and departures may be made therefrom within the scope of the accompanying claims without departing from the principles of the invention and without sacrificing its tages.

The present application is a continuation-inpart of my application Ser. No. 195,315, filed Mar. 11, 1938. i

What I claim is:

1. A'process of producing tungsten containing alloy steelwhich comprises adding ferrotungsten and a self-reducing mechanical mixture of tungstic oxide and a carbonaceous reducing agent to a molten ferrous alloy and thereafter adding a reducing agent to the alloy to reabsorb chief advancertain of the alloying ingredients which were oxidized by the addition of the tungstic oxide mixture.

2. A process of producing tungsten containing alloy steel which comprises adding self-reducing briquettes composed of a mechanical mixture of tungstic oxide and a carbonaceous reducing agent to a molten ferrous alloy and thereafter adding a reducing agent to the alloy to reabsorb certain of the alloying ingredients which were oxidized by the addition of the tungstic oxide mixture.

3. A process of producing tungsten containingalloy steel which comprises adding self-reducing briquettes composed of a mechanical mixture of an oxide of tungsten and a carbonaceous reducing agent to a molten ferrous alloy and there-- after adding a reducing agent to the alloy to reabsorb certain of the alloying ingredients which were oxidized by the addition of the tungstic oxide mixture.

4. A process of producing tungsten containing alloy steel which comprises adding self-reducing briquettes composed of a mechanical mixture of a lower oxide of tungsten and a carbona ceous reducing agent to a molten ferrous alloy and thereafter adding a reducing agent to the alloy to reabsorb certain of the alloying ingredients which were oxidized by the addition of the tungstic oxide mixture.

ARTHUR LINZ. 

